King pin lock for freight trailers



s w. LANGDON 2,630,699

KING PIN LOCK FOR FREIGHT TRAILERS March 10, 1953 Filed March 9, 1950 IN VEN TOR. SAMUEL W. LANGDON 28 l8 12 BY ATTORNEY Patented Mar. 10, 1953 Samuel W. Langdon,

Rochester, N. Y., assignor to Stephen L. Morrow, Webster, N. Y. Application March 9, 1950, Serial No. 148,690

This invention relates to a king pin lock for the freight trailer of a tractor-trailer unit for use while the tractor is uncoupled from the trailer.

Loaded freight trailers are often left unguarded either while coupled to or while uncoupled from their tractors, with the result that many loaded trailers have been stolen. The contents of these trailers are usually of considerable value so that such thefts represent high losses to the truck operators. While the tractor itself can be locked, the trailer can be readily disconnected therefrom and can be quickly coupled to another tractor, supplied by the thief, who can then drive away with the stolen trailer. If the loaded trailer has been previously disconnected from its tractor, by the owner, the thief merely needs to back his tractor into coupling relation with the king pin of the loaded trailer and then drive it away.

The present invention has for its purpose a novel trailer look so constructed that it cannot be readily burned away by a torch and cannot be quickly broken or disengaged by hammering or p ying.

The various features and advantages of the invention will appear from the detailed description and claim when taken with the drawings in which: 1

Fig. 1 is a fragmentary side view of the front portion ofa tractor-drawn freight trailer showing especially the conventional upper fifth wheel plate and the downwardly projecting king pin, with the lock of the present invention applied thereto;

Fig. 2 is a top view of the present lock with the bolt thereof in its locking position;

Fig. 3 is a section taken lengthwise on Fig. 2 particularly illustrating the king pin of the trailer having the lock thereon with the bolt of the lock in its locking position;

Fig 4 is a transverse section taken substantially on the line 4-4 of Fig. 3;

Fig. 5 is a view similar to that shown in Fig. 3 except that the king pin has been omitted and the bolt is shown in its unlocked position;

Fig. 6 is a cross-section taken substantially on the line B-6 of Fig. 5; and

Fig. '7 is an exploded perspective view of the bolt lock and its latch which retains the bolt in its locking position.

Referring first to Fig. 1, the numeral 5 designates the fragmentary front end 'portion of a freight trailer having the usual upper fifth wheel plate 6 with its conventional, grooved king pin 1 projecting downward therefrom so that the 1 Claim. (Cl. 70-232) is shown fastened to and completely enclosing the king pin 1 so that the trailer cannot be coupled to a tractor without removing the look. i

The lock comprises a hardened steel shell 9 which may be such as by casting the shell in two or more parts for easy internal machining and then welding these parts into an integral shell having the contours indicated in Figs. 1 and 2. As shown in Figs. 3 and 5, the right end of the casing is illustrated as having a heavy steel disc 9a welded thereto. This disc fills an opening through which a part of the interior of the casing was machined. This casing has a vertical cylindrical cavity 10 in the left end (Fig. 2) thereof to receive the king pin 1 as shown in Fig. 3. The right end of this casing has a longitudinally extendingrectangular guideway l l which communicates with the cylindrical cavity. This guideway receives the rectangular bolt l2 of the travel to and from the locking position (Figs. 3 and 5). It will be noted in Fig. '7 that the left end portion of the bolt has beveled upper and lower surfaces and a vertically extending, re entrant concave surface [3 to conform to and enter the notch la in the king pin. A coil spring I4 having its ends respectively retained in a bore in the right end of the bolt and in the bore IS in the casing, tends to move the bolt to its locking position as shown in Fig. 3, unless the bolt is otherwise retained in its unlocked position as shown in Fig. 5. p

The side of the bolt has a cam-shaped recess l6 provided therein to be engaged by a pin ll. This pin is carried by the cam l8 secured on the end of the cylinder IQ of a conventional cylinder lock, for moving the bolt I2 forward and backward. The top of the bolt has a latch recess 20 cut therein to receive the lower end of a generally rectangular latch 21 which insures that the bolt cannot be jarred from its locking position by hammering on the casing. This latch has a, lateral projection 22 with a rounded lower end 23 to be engaged by the periphery of the cam l8. A spring biases the latch downward so that the rounded end 23 is held in engagement with the cam at all times.

The casing is provided with a lateral circular bore which communicates with the guideway II. This bore is closed by a circular hardened steel plug 24 in which there is secured a conventional cylinder lock 25 arranged to move the bolt l2 between its unlocked and its locked tractor (not shown) made in any well-known manner lock with a sliding lit for.

position. This plug has a counter-bore in its circular surface to receive a set screw 26 accessible only from the top of the lock. It will be noted that when the lock is in its locking position on the king pin (Fig. 1) the top of the lock engages the under surface of the top fifth wheel plate so that the set screw is not accessible.

The plug 24 has a threaded bore extending therethrough*,.into which the barrel 28 of a conventional cylinder lock, can be screwed with the inner end of the cylinder I9 of the cylinder lock extending slightly beyond the plug. The inner end of the cylinder has mounted thereon the mentioned cam I8' having on its face the previous mentioned pin l1 which travels in the cam-shaped recess IS in the bolt, to move the bolt lengthwisein. either direction. The periphery of the cam l8engages the rounded lower end 23 on the latch projection 22., Thusthe cam l8 raises the latch 2| from the latch recess before the boltlZis shown) of. thecylinder lock. is turned in a clock-- thev cam l8-with its projecting pin I is also rotated in a: like direction from subwise; direction;

stantially-theposition shownin Fig. 5 to the position-shown in Fig. 3.. As the cam rotates, its

periphery starts to lower the latch 2| toward the latch. recess 20 and the pin I1 is carried'by the cam,. toward, thelef-t side: of the camrecess I 6. As: the-pin; i1; rotatesfurther inthis direction; it engages theleft side; of the cam recess its: full locking posit-ion, (Eighty, the. coil spring; l5 assisting in thislid to: force the bolt to.

movement: of the bolt. The key continues to, rotate. the cam. l8: until shoulder Isa, thereon engages. the leftside. of the latchZl (Fig. 3,) to stop-further. movement: of the'cam in the mentioned-direction. Atithis time the. pin llisouteside of the: cam recess; I G and the latchll is: fully lowere'dlintothe"latch-recess 2flso that the' bolt cannotbe dislodged from its looking position unless the cylinder lock is unlocked.

Whenit is desired t'o remove' thetrailer look from theking' pin; the key is inserted in the'cylinder lock; andis 1 turned in" a counter-clockwise direction: This rotates the cam I 8. and its" projecting pin IT in a like direction. As" the cam- IB rotates; it raisesthe latch Z-tfree-of the latch recess 20, so that the bolt 12 can be moved to the right wli'en th'e' pin I! engages; the vertical right'side of the" cam recess "5* tothe position the inner surface of moved by means: of. the pin H- toits.- unlocked position and lowers into. the latch recessshown in Fig. 5. The further counter-clockwise rotation of the cam l8 and the pin I! is stopped when pin I7 hits the shoulder 3| (Fig. '7) on the bolt.

In accordance with this invention, the lock preferably encloses the king pin completely but by way of modification the bottom of cavity I0 can also be left open so that the look only encircles the king pin.

From the foregoing it; will be seen that the present invention provides a trailer lock which is compact, which is easily applied to the king pin of the trailerrand which affords a high degree of' security against unauthorized removal.

While apreferred form of the present lock has been, disclosed. it, will be understood that there can be many modifications and variations therein, within the" scope of the appended claim, withoutrdeparting from the spirit of the present invention.

What I claimis:

A look for. the notched king pin which pro. jects downwardlfromthe upper fifth wheel plate of a, freight trailer, said lock comprisinga casing having. a portion enclosing the king pin about the notch therein, a bolt movable in said casing into and. out of. locking engagement with;

said notch, a latch for retaining said bolt in looking. engagement having a projection thereon,. cam recess therein. and a latch recess. therein, a cylinder lock secured in. the casing and. accessiblefor key operation from the outside there.- of, said cylinder lock being provided with a key.-

operated rotatable cylinder,v acam. on said cylin der for rotation therewith, said. cam serving tomove said latch into and out of engagement. with said latchrecesaand a pin on:saidcam engag-- ing said cam recess toadvance said bolt in engagement with the notch in said king pin and out of engagement therewith in coordinate relation with the lowering into and the raising respectively of the latch from therecess.

SAMUEL W. LANGDON;

REFERENCES CITED Thev following references are'of. record in the:

file of this patent:

UNITED STATES PATENTS:

with saidnotch, said latch. said bolthaving. a 

